Diagnosis and treatment of conditions affecting the brain are among the most difficult and complex problems that face the medical profession. The brain is a complex and delicate soft multi-component tissue structure that controls bodily functions through a complex neural network connected to the rest of the body through the spinal cord. The brain and spinal cord are contained within and protected by significant bony structures, e.g., the skull and the spine. Given the difficulty of accessing the brain through the hard bony protective skull and the delicate network and complex interactions that form the neural communication network contained within the brain that define the human body's ability to carry on its functions of speech, sight, hearing, functional mobility, reasoning, emotions, respiration and other metabolic functions, the diagnosis and treatment of brain disorders presents unique challenges not encountered elsewhere in the body.
For example, abnormalities such as intracranial cerebral hematomas (ICH), abscesses, glioblastomas (GB) and metastases (mets) manifest themselves in the intraparenchymal subcortical space (i.e., the white matter) of the brain are particularly challenging to access, let alone treat. The ventricles of the brain contain eloquent communication structures (neural network) which are located in the subcortical space, called fiber tracts and fascicles. Thus, traditionally, unless the ICH, GB, and/or mets where considered anything but “superficial,” such conditions have been considered inoperable, simply because getting to the abnormality ICH, GB and/or mets are considered just as damaging as letting the condition take its course. Similarly, tissue abnormalities such as tumors, cysts and fibrous membrane growths which manifest within the intraventricular space of the brain are considered challenging to safely access and often inoperable, due to their locations within the brain.
In order to assist in diagnosis and subsequent treatment of brain disorders, clear, accurate imaging of brain tissue through the skull is required. In recent years significant advances have been made in imaging technology, including stereotactic X-ray imaging, Computerized Axial Tomography (CAT), Computerized Tomographic Angiography (CTA), Position Emission Tomography (PET) and Magnetic Resonance Imaging (MRI), Diffusion Tensor Imaging (DTI) and Navigation systems (instrument position tracking systems). These imaging devices and techniques permit the surgeon to observe conditions within the brain in a non-invasive manner without opening the skull, as well as provide a map of critical structures surrounding an area of interest, including structures such as blood vessels, membranes, tumor margins, cranial nerves, including fiber tracts and fascicles. If an abnormality is identified through the use of one or more imaging modalities and/or techniques, it may be necessary or desirable to biopsy or remove the abnormality.
Once a course of action has been determined based upon one or more imaging techniques, a surgical treatment may be necessary or desired. In order to operate surgically on the brain, access must be obtained through the skull and delicate brain tissue containing blood vessels and nerves that can be adversely affected by even slight disturbances. Therefore, great care must be taken in operating on the brain so as not to disturb delicate blood vessels and nerves to prevent adverse consequences resulting from a surgical intervention.
Traditionally, accessing abnormalities which manifest in deeper spaces within the brain has meant a need for a surgery that creates a highly invasive approach. In some instances, in order to obtain access to target tissue, a substantial portion of the skull is removed and entire sections of the brain are retracted to obtain access. For example, surgical brain retractors are used to pull apart or spread delicate brain tissue, which can leave pressure marks from lateral edges of the retractor. In some instances, a complication known as “retraction injury” may occur due to use of brain retractors. Of course, such techniques are not appropriate for all situations, and not all patients are able to tolerate and recover from such invasive techniques.
It is also known to access certain portions of the brain by creating a burr hole craniotomy, but only limited surgical techniques may be performed through such smaller openings. In addition, some techniques have been developed to enter through the nasal passages, opening an access hole through the occipital bone to remove tumors located, for example, in the area of the pituitary.
A significant advance in brain surgery is stereotactic surgery involving a stereotactic frame correlated to stereotactic X-ray images to guide a navigational system probe or other surgical instrument through an opening formed in the skull through brain tissue to a target lesion or other body. A related advance is frameless image guidance, in which an image of the surgical instrument is superimposed on a pre-operative image to demonstrate the location of the instrument to the surgeon and trajectory of further movement of the probe or instrument.
In recent years, there has been a focus on developing surgical access systems to provide access to previously difficult to access areas. However, while access systems proposed so far may provide a manner to access certain brain tissue, such systems are configured with a blunt shaped distal end, which can actually cause transient or even permanent deformation and trauma of delicate tissue structures which can manifest itself in temporary or permanent neurological deficits after surgical cytoreduction due to damage of blood vessels, cranial nerves, fiber tracts and fascicles.
During a procedure, it is often necessary to protect certain critical vessels and/or structures that are adjacent an area to be operated on in the surgical field. It is known to use surgical patties to cover such vessels or structure. However, there are certain issues with known surgical patties.
First, known surgical patties are constructed of absorbent cotton gauze, which may be chemically bonded to one another to give the gauze a relative high wet strength. The resulting gauze structure has a surface that contains various absorbent fibers. As the surgical patty is left in place in the surgical field, the fibers become permeated by the fluid present and may tend to adhere to the body tissue to which the gauze structure comes into contact. Thus when the surgical patties are placed upon the tissue and moved along or removed from the surgical field, such movement can actually abrade and tear tissue, causing damage to the delicate neuro-vascular tissues that the patties are being used to protect from other instrumentation used during the procedure.
Another issue experienced with known surgical patties is the challenge of maintaining the position and location of the of the patty retrieval string during the surgical procedure to prevent them from falling into the surgical field during a surgical procedure. Known systems use locking surgical clamps called “snaps” or other similar devices to hold the position of the surgical patty string within the surgical field. When it comes to repositioning or removal of the patty within the surgical field, these holding devices must again be removed from the patty string to reposition the pattie and then re-applied.
Notwithstanding the foregoing advances, there remains a need for improved surgical techniques and apparatuses for operating on brain tissue. There also exists a need for improved surgical patties to address the specific challenges of minimally invasive neurosurgery, which includes the management of retaining and retracting of the strings for such patties.